The invention relates to a power source for supplying water-based liquid to a system, the power source comprising a container for the water-based liquid and a pump unit which consists of a pump and a power source for the pump and is arranged to supply the water-based liquid from the container to the system via a pipe system filled with a liquid.
Here the term `water-based liquid` means pure water or different water-containing additives, depending on the purpose for which the liquid is used.
Such a power source is particularly commonly used in various systems, e.g. in houses, for supplying water from a fresh water source, such as a well, to the pipe system of the house. Another application for a power source of this kind is a fire extinguishing installation.
The present invention also relates to a fire extinguishing installation, and particularly to a fire extinguishing installation comprising a spray head and a power source for supplying water-based liquid to a unit which is to be protected against fire, the power source comprising a container for the water-based liquid and a pump unit which comprises a pump and a power source for the pump and is arranged to supply the water-based liquid from the container to the unit via a pipe system filled with a liquid.
Certain environments where water or water-based liquid is to be supplied involve a risk of freezing. This problem is common in various situations in countries where the temperature drops below the freezing point of water. Some applications are related to a system without recirculation, i.e. a system where the amount of liquid decreases as it is used for a specific purpose. An example of the last-mentioned is a fire extinguishing installation which uses water-based liquid as extinguishant. In these it is particularly important that the extinguishant does not freeze because in that case the installation cannot work.
In several applications the problem of freezing is solved by mixing a substance which prevents freezing into water. However, the substances which prevent freezing, or antifreezes, are expensive; in fact much more expensive than water or water-based liquid. The larger the system and the liquid volume, the more expensive addition of antifreeze is. Because of this, the use of antifreezes in power sources with large containers involves the problem of high costs.
An example of applications where the above-mentioned problems occur is a fire extinguishing installation which is dimensioned for larger fires and in which the consumption of extinguishant is high. Furthermore, if antifreeze is mixed into water or water-based liquid in a fire extinguishing installation which uses water-based liquid, the resulting extinguishant will have a poorer extinguishing capability than a liquid into which antifreeze has not been mixed. Thus the use of antifreezes leads to a further problem of poor function.
To avoid high costs, substances which prevent the risk of freezing are sometimes omitted from the water-based liquid, which can have serious consequences in fire extinguishing installations, for example. The water-based liquid may also be replaced with a fluid which is harmful to the environment. Furthermore, in some cases the amount of water can be reduced, but in fire extinguishing installations, for example, this naturally involves a risk.